In This Section . . .

The Climate Impacts Group (CIG) issues a quarterly electronic newsletter designed to provide updates on regional climate and climate-related research, meetings, and topics of interest to Pacific Northwest (PNW) decision makers and resource managers. The first newsletter was distributed in January 2005.

1. Pacific Northwest Climate Outlook

NOAA issued an "El Niño advisory" on 9 July, which is a statement that the present and anticipated climate in the equatorial Pacific Ocean is consistent with warm ENSO ("El Niño") conditions. A discussion of equatorial Pacific climate is provided below. Presuming that the warm ENSO continues to develop as forecast, the impacts of this phenomenon on Pacific Northwest (PNW; Washington, Oregon, Idaho) climate will be seen beginning in the Fall months.

2. Pacific Northwest Streamflow Forecast Updates

The emergence of warm El Niño conditions by the end of June coincided with precipitation anomalies that varied spatially over the PNW during the months of April, May and June. Snow water equivalent (SWE) and soil moisture, predominantly determined by snowmelt and precipitation, were slightly above normal in April for southeastern parts of the PNW. By May the southern regions of the PNW exhibited more pronounced conditions of above average soil moisture, which increased through the beginning of July in the southeastern PNW. In contrast, SWE and soil moisture conditions were below normal over southern British Columbia and along the coastal regions in May. In southern British Columbia, soil moisture deficits (a measure of soil dryness) decreased through May and June (see initial conditions in the link to the archived forecast at http://www.hydro.washington.edu/forecast/westwide/archive/), and soil moisture was back to normal in July. During the same period, conditions of below average soil moisture expanded from the coasts of Washington and Oregon eastward towards central PNW, but limited to the mountain ranges.

The current warm phase ENSO (El Niño) event provoked normal to below normal soil moisture conditions by mid-July over wide areas in the PNW, with the notable exception of the southeastern region. SWE was also below normal, in contrast to last year’s above normal recorded values. Consequently, six month forecasts indicate that fewer than 15% of the Columbia River’s stations will maintain above normal streamflows, while forecasts for over 30% of the stations in the Snake River reveal values near or above normal. In the Columbia River basin, the stations forecasted to have below normal streamflows (70 to 90% of the mean) are predominantly in the lower reaches. In retrospect, last year’s forecast for stations along the lower Columbia River indicated between normal and above normal streamflows (90 to 110% of the mean). The Dalles station on the Columbia shows only 84% of mean streamflow, whereas forecasts for the station on Willow Creek, a tributary to the Snake River in Idaho, indicate streamflows exceeding 116% of the mean. These forecasts underpin the current dry and wet conditions in the western and southeastern regions of the PNW, respectively.

About the Forecasts. Graphical depictions of recent estimates of soil moisture, snow water equivalent, and streamflow can be found at the University of Washington's West-wide Seasonal Hydrologic Forecast System web site. These experimental real-time forecasts are updated twice monthly (1st and the 15th) and are based on several climate forecast methods. A number of products at the web-site are also updated on a daily basis. These include basin-averaged water balance conditions for each forecast point, spatial maps of current conditions, and a spatial summary of snow water equivalent for the western U.S.

A related effort that offers daily updates of hydrologic conditions throughout the U.S., can be
found on the UW Experimental Surface Water Monitor web site. The Surface Water Monitor shows
daily updating estimates of hydrologic conditions throughout the U.S. The site also offers
weekly projections for soil moisture and runoff across the U.S. for lead times up to 3 months.

3. Global warming impacts in the WA Cascades

Winter snowfall accumulation in the Cascades supplies much of the streamflow in the spring and summer as snow melts at higher elevations. Any shifts in snowfall accumulation resulting from a warmer climate have critical implications for various water-dependent resources, including drinking water supplies, fisheries, irrigation and hydropower in the Pacific Northwest. This crucial relationship served as the premise for research completed by Joseph Casola, doctoral candidate in the University of Washington’s Department of Atmospheric Sciences.

Casola’s study focused on measurements of water content in the snowpack over the last several decades. This metric, conventionally estimated as snow water equivalent (SWE) on April 1st of each year, is used to determine subsequent snowmelt and streamflow. Trends in records of SWE present on April 1 are difficult to relate to temperature changes since a variety of factors unrelated to temperature changes can influence annual snowfall. Consequently, trends calculated over different time intervals yield conflicting impressions as to the impact of warming. For example, measurements taken between 1944 and 2005 indicate a slight decline in snowpack, but measurements starting in 1950 and ending in 2005 shows a near tripling of that decline. Measurements taken over the last 30 years, a period of pronounced warming, point to a little or no trend in SWE.

Aside from warming, factors that can influence snowpack accumulation include large-scale climate oscillations like El Niño and La Niña, far-reaching climate phenomena emanating from the South Pacific Ocean (more information at http://cses.washington.edu/cig/pnwc/aboutenso.shtml). For example, El Niño years are associated with lower-than-average snowfall in the Puget Sound whereas La Niña years correlate to winters of high snow accumulation. Snowfall accumulation in the region is also affected by the Pacific Decadal Oscillation (PDO), a more prolonged climate cyclethat also contributes to lower (warm phase PDO) or higher (PDO) snow accumulation (more information at http://cses.washington.edu/cig/pnwc/aboutpdo.shtml).

To isolate the relationship between temperature and snowpack, Casola applied four different methods to determine the sensitivity of annual SWE to warming in the Cascades over the central Puget Sound. According to this work, if temperatures rise by 1oC, warming would cause more precipitation to fall as rain rather than snow and the central Puget Sound basin would lose 20% of its snowpack, assuming that precipitation does not change as a result of warming. This loss would result in lower spring and summer streamflows.

The results from this study, partly serving as Casola’s doctoral thesis, were published in the May 14th issue of the Journal of Climate, a publication of the American Meteorological Society. His co-authors include Lan Cuo, Ben Livneh, Dennis Lettenmaier, Mark Stoelinga, Philip Mote and John M. Wallace, all scientists at the UW. For a copy of the paper, please contact the CIG.

4. Wildfire and climate in the Western U.S.

Climate has a significant impact on the factors contributing to an ecosystem’s vulnerability to wildfires. Evidence points to complex relationships and positive feedbacks among projections of higher temperatures, prolonged fire seasons and fuel buildups provoking more intense and frequent fires. A comprehensive study headed by Jeremy Littell of the CIG, done in collaboration with other university researchers and U.S. Forest Service scientists, evaluated 19 ecosystem types from 11 Western States to investigate these relationships.

The study incorporates the fire data from 1916-2003 from ecosystems throughout the West to create models estimating total wildfire area burned. Comparing the results of these models to monthly state divisional climate data, the study quantified scientists’ long-standing notion that the susceptibility of mountainous forests to fire increases with lower precipitation and higher temperature during the summer. However, the study also reveals links between an ecosystem’s productivity and its fire susceptibility. For example, Western grass and shrubland ecosystems, which are generally not as productive as a forest ecosystem, require a season of high precipitation to boost productivity and generate fuel. A subsequent hot, dry season dries the abundant supply of fuel, increasing the probability of large wildfires in these ecosystems. Consequently, the role of climate change on fire susceptibility in Western states depends on the productivity and water limitations of the specific types of ecosystems. Climate can increase the severity and frequency of fires by enhancing the production and desiccation of fuel loads.

This information is potentially useful to managers in preparing for climate change. Plans for fuel treatments and fire suppression can be designed to target a specific ecosystem’s response to climate change. In woodland ecosystems, where the canopy is thin and fire does not play large role historically, short-term mitigation measures would involve fuel treatments to reduce fire risk and boost resilience. Whereas forested and shrubland ecosystems would not benefit from such tactics since drought dominates fire vulnerability in forests and the treatment would be ephemeral in shrublands.

This study indicates that as climate continues to warm, more areas in the West will become vulnerable to fire, particularly in the northern and mountainous forested regions, as expected. But less expected, this study reveals the possibility of cooler, wetter, less fire prone regions, like the western Cascades, becoming more susceptible to fire as extreme weather conditions increase during this century. It also suggests that some places in the Southwest and interior West could have less but more variable fire activity in the future if they were to become more arid.

This study was recently published in the journal Ecological Applications, with Jeremy Littell as lead author and Donald McKenzie, David Peterson and Anthony Westerling as his co-authors. For a copy of the paper, please contact the CIG.

5. NOAA announces the arrival of El Niño

A recent press release from NOAA announced that El Niño conditions are expected to persist through the 2009-2010 winter season. This climate phenomenon, characterized by a warming of equatorial Pacific waters, returns with a frequency of about every 2-5 years and its effects persevere for about 12 months. NOAA pronounced that the indices pointing to El Niño event have unequivocally manifested this season and will continue to develop over the next several months, possibly gaining greater intensity.

The ramifications of El Niño events are widespread. One effect is the abating of trade winds, which converge at the Inter-Tropical Convergence Zone (ITCZ) encircling the globe near the equator. The ITCZ materializes as a strip of clouds associated with the rainfall in and near tropical regions. Rainfall patterns during El Niño events shift, increasing over the central, tropical Pacific and decreasing over Indonesia and the central Amazon. El Niño-induced shifts in tropical precipitation result in droughts in the Amazon and Indonesia and devastating mudslides in Central and western South America. These changes in rainfall tropical regimes cause many of the divergent global weather patterns during El Niño events.

Other effects associated with El Niño in North America include a increased storminess in the South, destructive winter storms in California, warmer, higher winter precipitation in the Southwest, milder winters in the North, curbed hurricane activity in the Atlantic and reduced wildfire risk in Florida. Particularly for the Pacific Northwest, El Niño conditions are characterized by warmer, drier than average winters. Past El Niño events in this region have been associated with reduced snowpacks, which result in lower summer streamflows, water shortages, less hospitable salmon habitat and increased wildfire risk. On the beneficial side, El Niño years also include fewer winter/spring storms, lowering flooding and landslide risks. In marine ecosystems, El Niño can limit the weather conditions that provoke upwelling on the west coast, limiting nutrient circulation and productivity and negatively impacting food sources for marine organisms.

6.
Fall Forecast Meetings

The CIG's annual climate and water Fall forecast meetings for the 2010 Water Year have been scheduled. The Washington/Oregon Fall forecast meeting will take place on Tuesday, October 6, 2009 in Seattle, WA. The Idaho Fall forecast meeting will take place on Thursday, October 22, 2009, in Boise, Idaho. Meeting web sites and draft agendas are forthcoming. Topics that will be covered in the meeting include:

Climate change impacts to the water supply in the Yakima Basin and Puget Sound (Seattle)

Projected changes in extreme events and new developments in Regional Climate Modeling (Seattle)

Western water supply: Future directions (Boise)

Preliminary tree-ring reconstructions of streamflow in the Pacific Northwest (Boise)

7. King County's mapping tool to evaluate flooding vulnerability

King County, in collaboration with the Department of Natural Resources and Parks and the Wastewater Treatment Division (WTD), has developed a tool to determine the vulnerability of major wastewater treatment facilities to potential sea level rise and storm surges. The King County WTD maintains various facilities to collect and treat water from numerous communities in the Central Puget Sound region for the protection of water quality and public health.

The inundation vulnerability mapping tool was designed in response to growing evidence of increased future flooding at these facilities associated with climate change. The tool applies Geographical Information System technology to map the fixed elevation of WTD facilities and overlays different water levels projected under various climate change scenarios of sea level rise and tidal surges. The analysis conducted by the WTD includes 30 WTD facilities as case studies. The study found that 5 of the County’s facilities are at risk of inundation by 2050 from high rate of sea level rise coupled with a 100-year extreme tidal surge event. The probability of impact remains low until after 2050 according to the rates of sea level rise used in this report. The analyses completed using this tool were used not only to identify potentially vulnerable systems, but also to make recommendations for adaptive strategies.

8. New Washington legislation on climate change response strategy

The State of Washington reached an important milestone for adapting to climate change in spring 2009 with passage of Engrossed Second Substitute Senate Bill 5560 (E2SSB 5560) by the Washington State Legislature. The bill calls on the Washington Department of Ecology to work in partnership with the Departments of Agriculture, Natural Resources, Transportation, Fish and Wildlife, and Community, Trade, and Economic Development to develop an “integrated climate change response strategy” by December 1, 2011. The strategy will address the impacts of climate change and the state’s plans for preparing for and adapting to these impacts. In particular, the strategy will identify the following:

Priority planning areas for action, based on vulnerability and risk assessments;

Legal, policy, regulatory, and procedural barriers to adaptation at the state and local government level;

Opportunities to integrate climate science and projected impacts into planning and decision making; and

Methods to increase public awareness of climate change, its projected impacts on the community, and to build support for meaningful adaptation policies and strategies (Section 11(2)(b)).

E2SSB 5560 also asks State agencies to incorporate the adaptation planning strategy into agency policies and programs, including the design, planning, and funding of infrastructure projects.

9. The Center for Clean Air Policy reports on local adaptation efforts

The Center for Clean Air Policy (CCAP) underscored the importance of addressing climate change impacts on a local level by creating a partnership with leaders from ten city and county governments to galvanize local efforts for adaptation to climate change. Partners include leaders in Chicago, King County Los Angeles, Miami-Dade County, Milwaukee, Naussau County, New York City, Phoenix, San Francisco and Toronto. The program seeks to achieve the following objectives:

Promote the exchange of knowledge and information among partners;

Aid in the design and implementation of adaptation plans and programs;

Include local governments in the efforts to adapt to climate change impacts, particularly in urban areas;

Use the local implementation efforts as a model for developing national and state-wide policies and recommendations.

For example, Chicago released the Chicago Climate Action Plan in September of 2008, which provides a guide for the city’s plan to reduce greenhouse gas emissions. In King County leaders collaborated with the CIG to produce the adaptation guidebook, Preparing for Climate Change: A Guidebook for Local, Regional, and State Governments, providing a roadmap for responses to climate change by local governments and decision makers. Los Angeles is tackling the Urban Heat Island effect with the Million Trees LA program which partners community organizations with city agencies to plant trees along streets and in parks. In New York City, interagency stakeholders are collaborating to determine the vulnerability of coastal infrastructure to sea level rise and to implement programs to adapt to the impacts. All of these plans share a common characteristic of connecting local agencies and organizations to the effort to adapt and increase community resiliency to the impacts of climate change.
The full report, Ask the Climate Question: Adapting to Climate Change Impacts in Urban Regions, describes the focus of each partnership in detail and outlines frameworks for decision makers to address climate change locally.

10. National, regional impacts of climate change assessment

The United States Global Change Research Program (USGCRP) created a consortium of 13 government science agencies and several universities and research institutes to conduct an assessment of climate change in the United States. This well-regarded team recently released their findings in Global Climate Change Impacts in the United States. It represents the most comprehensive conclusions to date about climate change, its impacts now and forthcoming, over the entire U.S. It teases out the impacts of climate change by region and determines the implications for different socioeconomic sectors, like energy production, agriculture, human health and water resources. In the Northwest, the report focuses on the key concerns of declining spring snowpack, increased wildfires and insect attacks, habitat degradation of salmon and other coldwater species’ and coastline vulnerability to sea level rise.

The report proceeds to detail some of the options we have to respond to anthropogenic-induced climate change after establishing the underlying scientific evidence and its implications. It emphasizes the scientific basis for the decisions we face and the need for immediate action at the national and local levels.